Commit 53e9b626 authored Jun 17, 2020 by David Howells Committed by Greg Kroah-Hartman Jul 09, 2020

rxrpc: Fix afs large storage transmission performance drop



[ Upstream commit 02c28dffb13abbaaedece1e4a6493b48ad3f913a ]

Commit 2ad6691d988c, which moved the modification of the status annotation
for a packet in the Tx buffer prior to the retransmission moved the state
clearance, but managed to lose the bit that set it to UNACK.

Consequently, if a retransmission occurs, the packet is accidentally
changed to the ACK state (ie. 0) by masking it off, which means that the
packet isn't counted towards the tally of newly-ACK'd packets if it gets
hard-ACK'd.  This then prevents the congestion control algorithm from
recovering properly.

Fix by reinstating the change of state to UNACK.

Spotted by the generic/460 xfstest.

Fixes: 2ad6691d988c ("rxrpc: Fix race between incoming ACK parser and retransmitter")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 60d7de28

net/rxrpc/call_event.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -253,7 +253,7 @@ static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
		* confuse things
		*/
		annotation &= ~RXRPC_TX_ANNO_MASK;
		annotation \|= RXRPC_TX_ANNO_RESENT;
		annotation \|= RXRPC_TX_ANNO_UNACK \| RXRPC_TX_ANNO_RESENT;
		call->rxtx_annotations[ix] = annotation;

		skb = call->rxtx_buffer[ix];